NSLS and Beamline X3A ceased operations on September 30, 2014. Stay tuned for XAS@NSLS-II.

General Information

  • Beamline Operating Procedures
  • Beamline Shutdown Procedures
  • Research Program: Dual purpose macromolecular crystallography and X-ray absorption spectroscopy
  • Ring: X-Ray
  • Status: Operational
  • Time Dedicated to General User Program: 25% of operations
  • Participating Institutions: Case Western Reserve University, Rockefeller University, Sloan-Kettering Institute.



Energy Range
Crystal Type Bandwidth Flux Size of Focus
7.0 - 24
sagitally bent Si (220) 3 eV at 10 keV - 0.7 H x 0.08 V

3 mm vertical and 50 mm horizontal beam aperture in hutch. Horizontal width up to 38 mm possible.

Optical and Beamline Configuration

The beamline optical transport system operates under high vacuum and is enclosed by two Be windows. One 0.010 inch thick Be window is located in the front end 7.0 m from the source, while a second 0.008 inch Be exit window is located in the hutch 13 m from the source. A primary aperture assembly located 7.5 m from source provides pre-monochromator beam-defining slits.

A double crystal monochromator with fixed exit geometry is located 9.6 m from the source, with water cooling for the first crystal. The Bragg angle range is 7.55-28 degrees with a sagitally focusing Si(111) second crystal available as standard equipment. A flat cylindrically bent mirror located 11.2 m from the source is available for harmonic rejection and vertical focusing (0.08 mm FWHM). The mirror has separate Pd, ULE, and Pt stripes that can be translated into the beam path as needed. Mirror angle and focal length can chosen independently for variable beam size on the sample.

Experimental Apparatus

A 3m x 2.5m lead-lined steel radiation hutch is located 13 meters from the source, with independent equipment for both macromolecular crystallography and X-ray absorption spectroscopy present simultaneously inside the hutch. For macromolecular crystallography, a MAR 165mm CCD detector equipped with a motorized Z-lift for 2-theta, MAR rotation gionostat with super kappa geometry and an Oxford cryojet for cryocooling are available. Standard XAS equipment consists of a 13 element Canberra Ge fluorescence detector (12 functional elements) and a helium Displex cryostat attached to a vacuum chamber (14K sample temperature). Three transmission ion chambers with electronics (amplifiers, V/F converters, scalers) are available. Computer controlled X-Y aperture and X-Y-Z translation stages (500 lbs load capacity) are present for both XAS and MX measurements. Other user-provided experimental apparatus for XAS can be readily accommodated on the X-Y-Z translation stage with advance notice.

Computer System Hardware and Software

Beamline control and XAS data acquisition is provided a PC running Windows 8 and the NSLS XDAC Data Acquisition Software with CAMAC interface. A Windows 8 PC provides a Canberra software interface to the 13 element Ge detector. For crystallography data acquisition, processing, and analysis, a SGI Octane (2.8GHz dual processor) running Linux Red Hat Enterprise WS(v3) is available, with MARCCD software for data collection, HKL2000 for data processing, and an array of standard programs for crystal structure analysis and visualization. XAS data processing and analysis is available at the adjacent beamline X3B, using a Windows 8 PC with the EXAFS data processing programs Athena, Artemis, and Six Pack. DVD/RW drives and ethernet connections are present on all machines for data transfer. HP LaserJet 4050N and LaserJet P1005 printers are also available.

Publications resulting from use of beamline X3A must acknowledge the Center for Synchrotron Biosciences NIH grant P30-EB-00998 for supporting operations of beamline X3A.